A real time imaging based functional precision medicine (FPM) assay for glioblastoma

Functional precision medicine (FPM) assays, which test drug effects on live patient tumor cells, have the potential of personalizing therapy guidance for cancer patients. A number of FPM assays have been developed, the most common being based on measurements of “cell growth”. However, the majority of these measure “growth” of cells indirectly via bulk viability (e.g. Cell Titer Glo) as a surrogate for increased cell numbers within the assay by a defined time point but interpretation of such low dimensional data from complex tissues is often. We hypothesize that such assays could be improved if one were to ensure that patient cells being tested are healthy and growing before treatment ex vivo and could be analyzed for identity and morphology via single cell measurements. Furthermore, overall <50% of patient primary cells are expected to grow in culture and so faster measures could aid in more efficient testing for more patients. To address these areas and provide a simple assay able to be widely implemented in research or clinical labs, we designed and validated a miniaturized real-time growth assay based on Incucyte imaging of patient cells to monitor drug sensitivity response using the brain tumor glioblastoma (GBM) as an example. Ex vivo growth response was evaluated for the DNA damaging agent, Temozolomide (TMZ) - currently used as the standard of care for GBM patients, and KRT-232 - an MDM2 inhibitor currently in clinical trials. Patient cells were monitored every 6 hours until they met our treatment enrollment growth criteria of 3 consecutive increases of cell confluence and a minimum confluence of 10%. Patient cells were then eligible to be “enrolled” to the study, cultured as 2D cells in serum-free stem cell media, and treatments were then added. Cells were monitored every 6 hours for an additional 7 days. Initial validation of the method using long-term patient derived cell lines was performed followed by a co-clinical trial conducted in parallel with fresh GBM patient samples following patient consent. To date, 45 GBM patients have been screened in the study with 20/45 (44%) meeting the pre-determined growth enrollment criteria for ex vivo treatment and prospectively followed for which matched the expected rate of long term growth for GBM patient samples under these conditions. The assay was able to be successfully completed, and results generated for 17/20 (85%) of the subjects enrolled. Analysis of the ex vivo response profiles from the cohort were correlated with clinical parameters and known biomarkers of response ─ MGMT and TP53. Initial results suggest positive correlation with known parameters and reveal novel potential patterns of response. These results show feasibility and value of incorporating real-time functional growth monitoring to improve quality-control in functional precision medicine patient diagnostics. With further validation, this assay could become a valuable therapy guidance tool for clinicians.